java - What is the difference between @ManyToOne(optional=false) vs. @Column(nullable=false) -

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in jpa, confused when use attribute optional=false , annotation @column(nullable=false). difference?

@column(nullable=false) instruction generating schema. database column generated off class marked not nullable in actual database.

optional=false runtime instruction. primary functional thing related lazy loading. can't lazy load non-collection mapped entity unless remember set optional=false (because hibernate doesn't know if there should proxy there or null, unless tell nulls impossible, can generate proxy.)


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